The objective of the research is to develop and evaluate an oxygen-consumption meter (metabolic monitor), capable of breath-by-breath response. The stand-alone instrument is designed for use in anesthesia monitoring and features a small transducer assembly of unique design that is inserted between the tracheal tube and the anesthesia machine. The transducer assembly contains a low-resistance disposable and sterilizable pneumotachograph of a new design and a rapidly responding oxygen-concentration detector, also of a new design, operating on the principle of ultraviolet absorption. The oxygen uptake per breath is the volume per breath (measured with the pneumotachograph) multiplied by the difference in inspired and expired oxygen concentration. The metabolic monitor will indicate heart rate, respiratory rate, tidal volume and minute volume, as well as the oxygen uptake per breath and per minute, which is the minute sum of the uptakes per breath. The metabolic monitor will be evaluated on experimental animals under a variety of anesthesia conditions. Selected trials will also be made on human subjects under gaseous anesthesia.